supervisory authority concerned
as defined in GDPR, Article 4, point (22) (Definitions)
a supervisory authority which is concerned by the processing of personal data because: (a) the controller or processor is established on the territory of the Member State of that supervisory authority; (b) data subjects residing in the Member State of that supervisory authority are substantially affected or likely to be substantially affected by the processing; or (c) a complaint has been lodged with that supervisory authority;